on how flicks based on Alan Moore comics make Alan Moore very, very angry), but the thing I’d like to focus on is how it’s mildly surprising there’s a Watchmen movie at all. You see, for most of the time between the thematically dense graphic novel’s 1986 debut and now, the going line on Watchmen was that it was unfilmable.

Which is not to say that people haven’t tried: Watchmen was optioned as soon as it was published, with prominent directors like Terry Gilliam, Darren Aronofsky and Paul Greengrass attached to the project before 300‘s Zack Snyder finally sank his teeth in. It was Gilliam who first explained why it couldn’t be made: “The problem with Watchmen is that it requires about five hours to tell the story properly, and by reducing it to a two or two-and-a-half hour film, it seemed to me to take away the essence of what Watchmen is about.”

Whether Gilliam was correct or not is something science fiction and comic book geeks will discover for themselves this weekend, but the point to make here is that Watchmen isn’t alone in being a literary scifi property that has at one point or another been labeled as “unfilmable” even when (and sometimes even after) people have gotten it up on the screen. Here are some other examples:

DuneFrank Herbert’s book jammed together religion, politics, ecology, revolution and big honkin’ spice-excreting annelids into a text so dense it threatens to implode into itself. When David Lynch took it on in 1984 (apparently without having read the book before agreeing to direct — bad) he added his own layer of weirdness to it, and the result was confusing enough that the studio felt obliged to offer flyers to moviegoers explaining what was going on. A 2000 TV miniseries of the book made substantially more sense, but felt flat and chintzy, not nearly conveying the scope of the book. But hope (and spice) springs eternal, as Hancock director Peter Berg is scheduled to take a swing at it in the near future. Good luck.

Stranger in a Strange LandRobert Heinlein’s 1961 satire of religion is arguably the most influential science fiction novel of all time, but presents unique challenges as a movie, not the least of which is how to convince studios craving the financial sweet spot of a PG-13 rating that the world needs a flick featuring religion with sex as a sacrament and clothing-optional group marriages. Then of course there’s the old guy who lectures everyone who comes near him on morality, religion and basic interpersonal relationships. Stranger is not currently in any stage of production (but I would love to see what Darren Aronofsky could do with it).

The Foundation SeriesIssac Asimov’s epic series of books are science fiction’s closest answer to a Calvinistic sense of predestination — i.e., “civilization is going to fall anyway, we’re just trying to contain the splashback.” The series is chockful of ideas about human mass psychology, which are something of a challenge to portray in a way that will both satisfy fans and popcorn-munching masses. Foundation is currently optioned by Roland Emmerich, and it will be interesting to see if the maker of fun but brain-free offerings like Independence Day can thread this particular intellectual needle.

Ender’s GameOrson Scott Card’s novel of an unwitting child warrior is one of the most popular science fiction novels of the last quarter century, and has been in various stages of pre-production and adaptation over the years. Its challenge, unlike so many other titles here, is not that it is a weighty tome or series. The major problem is that its main character is five. It’s one thing to imagine in text a remarkably precocious five-year-old; it’s another thing to show one using an actual five-year-old actor. Scifi geeks are itchin’ to see this on the silver screen anyway, and while at the moment Ender doesn’t appear to be under option, it’s only a matter of time.

And yes, I would go see these all.

Got a favorite (and popular) science fiction book you consider unfilmable? What is it? And would you go to see the movie anyway if they made it?

Winner of the Hugo Award and the John W. Campbell Award for Best New Writer, John Scalzi is the author of The Rough Guide to Sci-Fi Movies and the novels Old Man’s War and Zoe’s Tale. He’s also Creative Consultant for the upcoming Stargate: Universe television series. His column appears every Thursday.